The woman with Zika, who is not pregnant, hasn’t traveled to any countries with ongoing virus transmission, but her infection was confirmed by a lab test last week, according to the Texas Department of State Health Services.

“We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas. We still don’t believe the virus will become widespread in Texas, but there could be more cases, so people need to protect themselves from mosquito bites, especially in parts of the state that stay relatively warm in the fall and winter,” said DSHS commissioner Dr. John Hellerstedt.

During testing, the unnamed patient from Brownsville, was found to have the Zika virus in her urine. But a blood test came back negative — indicating that “the virus can no longer be spread from her by a mosquito,” according to the DSHS.

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In coordination with the Centers for Disease Control and Prevention, the Texas DSHS is investigating the Brownsville case to find out how and where the infection occurred. Health officials will be going door-to-door in the area, requesting voluntary urine samples looking for other infections.

“Brownsville has recently sprayed for mosquitos in the area and will continue to take action to reduce mosquito population,” the DSHS said in a statement.

Texas now has 257 confirmed cases of the Zika virus, but until now all cases were associated with travel (including two babies born to females who had traveled during pregnancy).

Florida, the only other state with a confirmed locally transmitted case, has a staggering 238 cases of locally acquired Zika infections and 953 travel-related infections. The number of pregnant women with lab-evidence of Zika is up to 170.